Lowering hanger with constant tension



' July 9, 1957 T. B. FARRINGTON ETAL LOWERING HANGER WITH CONSTANT TENSION Filed July 5, 1951 2 Sheets-Sheet l INVENTORS f-mnw B. E'NRINGTON fimsikr If. l-hliwnvarolv Uite States Patent Office 2,798,680 Patented July 9, 1957 LOWERING HANGER WITH CONSTANT TENSION Thayer B. Farrington, Cleveland Heights, Robert K. Farrington, Shaker Heights, and Harold L. Dalzell and Richard F. Kurzenberger, Cleveland, Ohio, assignors to The Thompson Electric Company, Cleveland, Ohio, a corporation of Ohio I Application July 5, 1951, Serial No. 235,314

4 Claims. (Cl. 242--107.13)

This invention relates to improvements in disconnecting and lowering lamp hanger structure.

One of the objects of the present invention is to provide, in a disconnecting and lowering lamp hanger structure of the type described, a compact means always exerting a substantially uniform force or tension on the lowering member to counterbalance its weight.

Another object of the present invention is to provide in a disconnecting and lowering lamp hanger structure of the type described a pulley on either the fixed or lowering member with said pulley surrounded by a bight of a flexible raising or lowering cable to equalize tension in the cable rims, thus avoiding tilting of the lowering member in any unlatched position.

Another object of the present invention is to provide in a disconnecting and lowering lamp hanger structure of the type described a novel separable fastening or latching element to retain the lowering member to a fixed member in its elevated or normal position.

Another object of the present invention is to provide in a disconnecting and lowering lamp hanger structure of the type described a separable fastening or latching element to retain the lowering member to a fixed member in its elevated or normal position and a latch operator adapted to receive a detachable mating rod held by a person on the floor beneath said lighting apparatus. The rod is adapted to actuate said latching element and to raise or lower said lowering member. The rod is designed so that it cannot be removed from the operator when in hanger-unlatching position. The rod is also designed so that, when the latch is unlatched, the rod is automatically hooked to the lowering member in position to pull the iatter downward.

Another object of the present invention is to provide in a disconnecting and lowering lamp hanger structure of the type described, means for performing any combination of the functions set forth above.

Other features of this invention reside in the arrangement and design of the parts for carrying out their appropriate functions.

Other objects and advantages of this invention will be apparent from the accompanying drawings and description and the essential features will be set forth in the appended claims.

In the drawings,

Fig. 1 is a longitudinal sectional view of the lighting apparatus of this invention;

Fig. 2 is a vertical sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a vertical sectional view taken along the line 3-3 of Fig. 1;

Fig. 4 is a vertical sectional view enlarged taken along the line 44 of Fig. 1;

Fig. 5 is a vertical sectional view similar to Fig. 4 but showing the lowering member connected to the fixed member;

Fig. 6 is a horizontal sectional view taken along the line 6-6 of Fig. 5;

. winding reels.

Fig. 7 is a sectional view taken along the line 7-7 of Fig. 5;

Fig. 8 is a bottom view of the spring counterbalance means taken along the line 88 of Fig. 1;

Fig. 9 is an enlarged view taken along the line 9-9 of Fig. 1; while Fig. 10 is an enlarged top view of the fastening element taken along line 1010 of Fig. 5.

The lighting apparatus of this invention consists of a relatively fixed member 10 generally attached to the ceiling of a room to be lighted. A lowering member 12 is adapted normally to occupy a raised position adjacent to and latched to the fixed member. It can also be unlatched and lowered therebelow so that the lamp means 13 may be replaced therein when it burns out. A ballast or transformer 11 may be attached to either the fixed member or the lowering member, which. ever is desired. Fig. 1 shows the ballast attached to the fixed member 10. Mating electrical contacts 14 on the lowering member and 15 on the fixed member are adapted to be engaged when the members are latched together. Contacts 15 are supplied with electricity through means not shown. Although the drawings illustrate only four contacts on each member, this invention contemplates that any required number can be used on each member.

, The contacts 14 are also spring loaded so that the fastening or latching element, to be later described, may function to hold the members together and so that the contacts 14 and 15 will always have a good electrical contact. This feature of spring loading: the contacts is also disclosed in the copending application of Thayer B. Farrington, Wade T. Keller and Harold L. Dalzell on Overhead Mounting for Tubular Lighting Fixtures, Serial No. 589,822, now Patent No. 2,564,328, filed April 23, 1945, and assigned to The Thompson Electric Company, Cleveland, Ohio. In the present application, contacts 14 are mounted on blocks 14a of porcelain or other insulating material. These blocks are carried on a floating bracket 14b having lateral pins 14c loosely engaging vertical slots 14d in lowering member 12. Bracket 14b is biased upwardly by leaf springs 14e. Each contact 14 is adapted to resiliently engage each contact 15 with equal pressure regardless of their alignment since bracket 1411 may freely float and align the contacts. Of course, other types of resilient means may be used in place of springs 14c, if desired.

Extensible and retractable flexible supporting means, generally indicated at 16, connect the members together. There is an extensible and retractable supporting means equally spaced on each side of the center of the lighting apparatus. The approximate center is along the vertical portion of line 44 of Fig. 1. Since both means 16- illustrated in Fig. 1 are identical, the same corresponding reference numerals will be used on the corresponding parts of each, and only one of the means will be described. A freely rotatable pulley 17 is mounted on the lowering member 12 and has the bight of a flexible cable 18 surrounding it. This pulley 17 permits the member 12 to always occupy a level position regardless of uneven winding of cable 18 upon its two A spring counterbalance means, generally indicated at 21, is operatively connected with the free ends of each cable 18 to reel in the cable to raise the lowering member 12 or to reel out the cable to lower it. Of course, as long as pulley 17 is connected to one member and the spring counterbalance means is conmember 10 with the spring counterbalance means being.

mounted on the lowering member 12. However;

prefer to keep as much mechanism as possib For example, the pulley 17.

fixed member. The spring counterbalance means 21 is in driving connection with the coaxial reels 22 and 23. These reels are connected to rotate together and one reel is attached to each free end of the cable 18. The reels and the spring counterbalance means are rotatably mounted between flanges 19 and 20 of the fixed member 10. Guide pulleys 22a and 23a, each loosely mounted on shaft 24 so as to slide longitudinally and rotate thereon, cause the cable to wind evenly on reels 22 and 23, respectively. Of course, this invention contemplates an alternative construction in which one of the free ends of the cable 18 may be .fixed or anchored to the member 10 while the other end is attached to a reel 22. In this structure, reel 23 would be eliminated.

The spring counterbalance means 21 is a compact mechanism providing'a substantially constant torque to the reels 22 and 23 and a substantially constant force or tension to the flexible cable 18 so as to counterbalance the weight of the lowering member 12 It contains two spaced rotatably mounted drums 25 and 26. These drums have parallel'axes with drum 25 being larger than drum 26. A strip of spring steel 27 is wound around them and drivingly connects them together. This strip is attached todrum 25 and winds upon itself on drum 26. The natural curvature of this strip is of such a degree that the spring is in equilibrium when it is spirally wound on the smaller diameter drum. When the lowering member 12 is lowered and the cable is payed out, the strip moves from the smaller diameter drum to the larger diameter drum. The larger diameter drum is rotated in such a direction as to back-bend the strip in a spiral opposite in direction to that form it maintains on the small r diameter drum. The tendency of the spring is to return to its original position; this gives the tension to the cables 18 and the lowering member 12. There are apparently two reasons for the uniform tension or torque exerted by this spring counterbalance means. First, the effective length of the spring is that extending between the two points of tangency on the larger and smaller drums. Since this length of spring remains substantially constant, the tension on the cable 18 and the torque on the reels 22 and 23 is substantially constant. Second, the torque may be made constant throughout the length of the strip 27 by controlling the prestressing of the spring strip. The torque produced is a function of the amount the portion between the reels 22 and 23 is deflected from its free position. The greater the differences in radius of the 22 and 23, the larger will be the torque de veloped. Hence, the maximum torque in a minimum space is produced by back-bending the spring strip 27 from one reel to the other, as set forth above. Even though two spring counterbalance means 21 are shown in Fig; l, the invention contemplates that these may be replaced by a single unit drivingly connected with the reels 22 and 23 on the left and on the right side of Fig. 1.

counterbalance means used heretofore have not provided a constant tension or torque to counterbalance the lowering member in any position that it might assume. For example, a normal helical spring would follow Hookes law and the counterbalancing force, tension or torque would be directly proportional to the displacement of the lowering member. The counterbalancing force would be much too great when the lowering member assumed one of its extreme positions while the force would be much too small when the lowering member assumed its other extreme position of vertical displacement. Free falling counterweights counterbalancing the lowering member would furnish a constant tension or torque on the lowering member, but the counterweights would require too much space and could not be contained in the compact volume subtended by spring counterbalance means 21'. I This invention has truly solved a problem that has puzzled the engineers in the lamp hanger field for many years.

The members 10 and'12 are separably held together Li, by a positive latch 30 positioned centrally of the members. We prefer a bayonet joint type of latch with some resiliency in the latching action. The specific type of latch shown consists of a short resilient wire length 31 attached to the top of member 10 by rivets 32 and 33. The wire length 31 is so spaced in the member 10, as seen in Fig. 4, to provide resiliency in the latching connection. The latch also includes a fastening element or shank 34 rotatably attached to the lowering member 12 by a C-shaped retainer ring 34a held in place by a guide ion. The shank has on each end an axial bore with cylindrical walls. Two slots, generally indicated at 35, are formed in the cylindrical walls at the upper free end of the shank. Each of the diametrically opposite corresponding slots has its entrances 36 at the upper free end of the shank, Each slot has an inclined camming surface 37 extending from its entrance 36. A locking offset 38 is located at the end of the camming surface. This locking offset is closer to the free end of the shank than the peak of the adjoining camming surface. Hence, resilient wire length 31 is bent slightly downward and is positively held in the locking offset when the lowering member 12 is in its elevated position, as shown in Pig. 5, or may be detached therefrom so that the lowering member 12 may be lowered, as seen in Fig. 4.

The fastening element or shank 34 has a downwardly directed operator 4%) for the latch formed on its lower end. A downwardly directed slot 39 is formed in the cylindrical wall on the operator end of the hollow shank 34. Mating rod 42 may be held by a person on the floor beneath the lighting apparatus to engage the operator so that the lowering member 12 may be raised or lowered. The mating rod has a pin 43 adapted to slide in the slot 39 as the upper end of the rod telescopes into the operator 40. A flared guide 40a surrounds operator {it and guides the upper end of the pole into the operator. Guide 40a also has a longitudinal slot in its base. A slot 39a is formed in the bottom plate of lowering member 12. This slot 39a is aligned with slot 35! when members 10 and 12 are latched together by wire length 31 in offset 38. As rod 42 is inserted into the operator of Fig. 5, the pin 43 is adapted to travel the full length of slots 39 and 39a so as to be positioned between the upper end of the operator 4t and the top surface 44 of the bottom wall of the lowering member 12. When the rod is rotated 90 degrees and pin 43 engages stop 45 of member 12, the shank 34 is rotated by pin 43 and the wire length 31 is forced out of offsets 38 toward entrances 36 of the slots. Then, the pin 43 is firmly held between the surface 44 and the upper end of operator 48 to form a locking connection similar to a bayonet joint. Member 12 may be lowered by rod 42 for service and then later raised to its elevated position. When the light means 13 is energized, the rod operator knows that slot 35 is in its normal position to receive wire length 31. Springs We keep contacts 14 and 15 firmly'held together while permitting shank 34 to travel still farther upwardly until wire length 31 is firmly engaged in the locking offset 38. It should be noted that once the wire length 31 enters the slot 35 and the pole is rotated, the pole cannot be withdrawn from the operator until the wire length 31 is again firmly secured in offset 38 to latch members 19 and 12 together. Then, pin 43 has engaged stop 45a and has aligned slot 39 with slot 39a so that the pole may be withdrawn from the operator.

The spring counterbalance means 21 is adjusted to provide a constant tension or torque to just counterbalance the weight of the lowering member 12. Then, the lowering member will stay in any elevated position selected and will have no tendency to go up or down. The person on the floor beneath the lighting apparatus may raise or lower the member 12 by pushing or pulling the rod 42 until the lowering member 12 is at the desired position. It should now be clear that the lowering member 12 may be readily lowered so that the lamp means 13 may be replaced, and then the member 12 may be raised and then latched to fixed member on the ceiling to assume its normal position. The spring counterbalance means 21 is a compact mechanism providing a substantially constant tension on flexible cables 18 so that the member 12 may be lowered and raised with a minimum of efiort.

What we claim is:

1. In lighting apparatus of the type wherein a relatively fixed member is supported in an elevated position and a lowering member is adapted to occupy a raised position adjacent and latched to said fixed member or to be unlatched and lowered therebelow; a plurality of flexible cables between said members and equally spaced on each side of the center thereof, a substantially constant ten sion counterbalance spring drive means on one of said members connected with said flexible cables to wind up or pay out the cables at a uniform counterbalanced rate as said lowering member is respectively raised or lowered, said constant tension drive means including two spaced drums of diiferent diameters rotatably mounted on parallel axes, the larger diametered drum drivingly connected to at least some of said cables to wind them up or pay them out at a uniform counterbalanced rate, a strip of spring steel drivingly connecting the drums and having a natural curvature of such a degree that the spring will be in equilibrium when it is wound on the smaller diametered drum, said strip being normally stored in tightly wound condition on said smaller drum, and said larger diameter drum being rotated in a direction to back-bend said strip in a spiral opposite to that on the smaller diametered drum when said cable is payed out as said lowering member is lowered.

2. The combination of claim 1 wherein there are two of said flexible cables equally spaced on each side of the center of said one member, a pair of pulleys rotatably mounted on said other member in position below said cables respectively, and each of said pulleys receiving a bight of its associated cable around the pulley, whereby said lowering member always occupies a level position regardless of uneven reeling of the cable.

3. In lighting apparatus of the type wherein a relatively fixed member is supported in an elevated position and a lowering member is adapted to occupy a raised position adjacent and latched to said fixed member or to be side of the center thereof; a plurality of reels, each reel connected to a flexible cable; and a plurality of substantially constant torque counterbalance spring motors on one of said members, each motor connected with one of said reels to wind up or pay out the cables at a uniform counterbalanced rate as said lowering member is respectively raised or lowered; each spring motor including two spaced drums of difierent diameters rotatably mounted on parallel axes, the larger diametered drum drivingly connected to its associated reel, and a strip of spring steel drivingly connecting the drums and having a natural curvature of such a degree that the spring will be in equilibrium when it is wound on the smaller diametered drum, said strip being normally stored in tightly wound condition on said smaller drum, said larger diametered drum being rotated in a direction to back-bend said strip in a spiral opposite in direction to that on the smaller diametered drum when said cable is payed out as said lowering member is lowered.

4. The combination of claim 3 including a pair of pulleys rotatably mounted on said other member in position below said cables respectively, and each of said pulleys receiving a bight of its associated cable around the pulley, whereby said lowering member always occupies a level position regardless of uneven reeling of the cable.

References Cited in the file of this patent UNITED STATES PATENTS 727,486 Sundin May 5, 1903 1,493,436 Kubista et a1. May 6, 1924 1,955,740 Dzus Apr. 24, 1934 2,439,885 Darley Apr. 20, 1948 2,564,101 Dzus Apr. 14, 1951 2,564,328 Farrington et a1. Aug. 14, 1951 2,581,083 Drury Jan. 1, 1952 2,585,241 Gunther Feb. 12, 1952 2,614,306 Dzus Oct. 21, 1952 FOREIGN PATENTS 26,296 Great Britain May 3, 1906 450,134 France Mar. 15, 1913 

